Patent Literature 1: JP 2010-509825 A (US 2008/0107027 A1)
There is formed a ring topology of a network of Ethernet (registered trademark) by connecting a plurality of Ethernet switches (hereinafter, referred to as a switch) as relaying apparatuses.
Such ring topology includes two communication routes between the respective switches. For instance, each switch has (i) two ring ports used for the ring connection and (ii) non-ring ports via which an apparatus is connected with the switch. Suppose that a subject switch transmits, via each of two ring ports, a frame whose transmission destination is an apparatus with which a different switch is connected via a non-ring port of the different switch. Then, the transmitted frame is inputted into the different switch via each of the ring ports of the different switch. This signifies that two communication routes are provided between (i) an apparatus with which a subject switch is connected via a non-ring port of the subject switch and (ii) an apparatus with which a different switch is connected via a non-ring port of the different switch.
Another technology disclosed in Patent literature 1 is to perform a frame transmission between nodes using a predetermined shortest route.